Ultrasonic Waveguides Detection-based approach to locate defect on workpiece

Conventional ultrasonic techniques, such as pulse-echo, has been limited to testing relatively simple geometries or interrogating the region in the immediate vicinity of the transducer. A novel, efficiency methodology uses ultrasonic waveguides to examine structural components. The advantages of this technique include: its ability to detect the entire structure in a single measurement through long distance with little attenuation; and its capacity to test inaccessible regions of complex components. However, in practical work, this technique exists dispersion and mode conversion phenomena which makes poor signal to noise ratio, thereby, influences the actual application of this technique. In order to solve this problem, simulation with experiments can not only verifies the feasibility of this technique, but also has guiding significant for actual work. This paper reports on a novel approach in the simplification of the simulation of Ultrasonic Waveguides Detection. The first step is the selection of the frequency of signal which has the fastest group velocity and relatively small dispersion. The second step is the decision of Δ and l_e. As the numerical analysis characteristics of general-purpose software ANSYS, two key parameters: time step Δt and mesh element size l_e need to be carefully selected. This report finds the balance point between the accuracy of results and calculation time to determine two key parameters which significantly influence the result of the simulation result. Finally, this report show the experiment results on two-dimensional flat panel structure and three-dimensional triangle-iron structure respectively. From the result shown, the error between the simulation and actual value is less than 0.4%, perfectly prove the feasibility of this approach.